Purpose:
Determine the effect of b2adrenergic receptor and eNOS genotypes on:
? severity of hypotension after spinal anesthesia
? response to ephedrine (b2 agonist) and phenylephrine (a agonist)
Sample size: 200 elective C/S under spinal anesthesia
Exclusion: chronic or pregnancy-induced hypertension, with or without treatment
Protocol:
? BP (3 measurements) should be recorded 30 minutes after arrival at L&D in supine position with LUD (baseline BP)
? Fluid preload: 1000ml RL for case starting 8-9 AM; 125 ml additional for every hour after 9 AM
? Spinal procedure: sitting position (L2-L3, L3-L4, L4-L5), 2.5ml solution (12mg hyperbaric bupivacaine & 25mg fentanyl & 200mg morphine)
? Stopwatch starts upon beginning of injection of the spinal solution
? BP, HR, %O2 sat q1 for the first 15 minutes, then q5
? Anesthetic level to ice q5 according to data collection sheet
? Record each ephedrine and phenylephrine dose according to timing
? Record skin incision time, uterotomy, delivery time
? Record baby weight, Apgar and cord gas (pH)
? Record staples/completion of skin suture time
? Blood sample (2 purple top tubes) any time (during C/S, or on PP day 1) labelled with patient name and MRN
? Record ?baseline SBP? (mean of 3 measurements pre-op)
? At each 1 min SBP measurement
? If decrease > 20% from baseline BP or < 90 mm Hg ? ephedrine 5-15 mg
? If inadedquate response after ephedrine 30 mg ? phenylephrine 40-80 mg, may repeat ephedrine
? If hypotension and HR > 120 ? phenylephrine 40-80mg
? Above doses may be exceeded if clinical conditions warrant--- record all doses)